Three-Component Synthesis of Functionalized Pyridines

Significance

Reported is a study of the scope of a three-component pyridine-forming reaction which was discovered earlier by Reissig and co-workers (Chem. Eur. J. 2004, 10, 4283). The reaction affords highly functionalized pyridines containing, for example, two differentiated oxygen functions, thus allowing opportunity for selective Pd-catalyzed cross-couplings. The scope of the reaction with respect to carboxylic acids, nitriles, and alkoxyallenes is reasonably broad and the products are obtained in poor to good yields. Furthermore, the use of dinitriles allows the synthesis of complex dipyridyl derivatives. The overall yields from the latter reaction are poor, but one has to consider that eight new bonds are formed in one transformation.